Attempts have been made to eliminate the need for multiple length socket sets in ratchet wrench design without sacrificing structural integrity, reliability or ease of use. Early attempts focused on designs of ratchet wrenches having a hole through the wrench centered on the axis of rotation of the drive portion of the ratchet wrench. U.S. Pat. No. 125,695 to Sanborn, U.S. Pat. No. 1,165,995 to Mossberg and U.S. Pat. No. 2,317,461 all disclose a ratchet wrench with a through hole. The wrench in each of these patents is adapted for only a single fastener size. U.S. Pat. Nos. 1,347,691 to Forton, 4,328,720 to Shiel, and 2,300,479 to Wilson each discloses a ratchet wrench with a through hole which is adapted for using interchangeable sockets enabling the use of the wrench with a range of fastener sizes. U.S. Pat. Nos. 4,520,697 and 4,602,534 to Moetteli disclose a ratchet wrench having a through hole and which is adapted for use with multiple sockets. The later two patents to Moetteli disclose a reversible ratchet wrench which eliminates the need for multiple length socket sets through the use of special sockets which are comparable to the weight, compactness, strength and size range of standard square drive sockets. Though the latter two patents describe an invention which overcomes most of the disadvantages and shortcomings characteristic of the earlier through-hole designs, it is not successful in duplicating the retention force typical of a standard ratchet wrench's spring-and-ball detent without a concomitant sacrifice in structural integrity.
Proper retention of a socket is an important feature of wrenches because it prevents the inadvertent disengagement of the socket from the drive portion of the wrench. Inadvertent disengagement can result in extreme inconvenience for several reasons. First, the socket may become much more difficult to position over the fastener if it is not held in place on the drive and maneuvered by the operator's hand remotely through the ratchet wrench's handle. Second, the socket may become lost in some remote recess, or become temporarily unretrievable due to its becoming lodged in a recess near a very hot component of an automotive engine thus making safe retrieval difficult. Third, although the operator may be able to successfully remove the ratchet, the socket may remain on the fastener thereby becoming difficult or impossible to remove without expending excessive time to do so. Fourth, due to their additional weight, the ratchet may not be able to adequately retain commonly used accessories on the drive member such as a universal joint or extension; this will result in still more difficulty in accessing a fastener for removal or installation. Fifth, the socket may slip off the drive during wrenching with the possible result being damage to the ratchet or socket and/or injury to the operator.
In standard ratchet wrenches adapted for use with a socket set, it is common to provide a spring-and-ball detent to secure the socket on the drive member of the wrench during use. Generally, this has provided adequate retention such that the five problems mentioned above can be avoided. Characteristic of a spring-and-ball detent is the requirement of a relatively thick section on the drive member in order to accommodate the enclosure the spring and the ball. However, because a thin-wall is created in the drive portion when the wrench has a through hole and (1) has an inner and outer drive or (2) has a drive portion which protrudes beyond the drive member of the wrench, there is insufficient material to support this conventional means for retaining a socket on the drive.
U.S. Pat. No. 2,549,515 to Orey et al describes a thin-wall through-hole wrench that utilizes resilient members disposed within a key-way type recess in the thin-wall sleeve to restrain the sockets onto the sleeve or drive portion. These resilient members provide adequate retention of the sockets onto the sleeve; however, the resilient member and key-way recess retain a socket from one side of the drive portion only, not from both surfaces of the drive portion as provided in the present invention. Also, no means is described for the mounting of the resilient member onto the drive portion. In the invention as described in U.S. Pat. No. 4,328,720 to Shiel, the means provided for retaining a socket was that of a resilient annular wire disposed within the thin-wall portion of the drive member. This too may provide adequate retention of a socket, but it also requires that a recess be machined into the drive portion in which the wire may be disposed. This recess weakens the drive portion as it lies within a plane substantially perpendicular to the torsional axis of the wrench.
The hand tool described in U.S. Pat. No. 1,413,698 to Adams discloses a spring clip formed of a resilient strip of metal. This clip is designed to hold shanks or sockets within the drive portion. It would therefore be ineffective for retaining sockets either on the outside or the inside of the drive portion. In addition, the spring clip requires that a reduced thickness portion be machined or molded onto the thin-wall portion of the drive member. This reduced thickness portion compromises the structural integrity of the drive portion against torsional stresses induced through normal operation of the hand tool.
The swivel knife described in U.S. Patent No. 2,803,877 to Belanger discloses a V-shaped retainer spring for the purpose of retaining an internal tool shank and an outer collar. This retainer spring does not function independently but requires a cylindrical component referred to as a locking means in order to retain the tool shank inside the stud.
The ratchet wrenches described in U.S. Pat. Nos. 4,520,697 and 4,602,534 to Moetteli above recites incorporate several methods for retaining a socket to a drive member having a thin-wall drive portion. A first method incorporates a push-button release feature which allows the operator to remove a socket by depressing a resilient button or comparable element. A second method utilizes a resilient spring clip which snaps in place over the thin-wall portion of the drive member in a manner similar to a paper clip. However, the first method utilizes a spring which is relatively complicated and costly to produce and the second method utilizes a spring clip that requires that a reduced thickness portion be machined or molded onto the thin-wall portion of the drive member. Furthermore, this spring clip is unsatisfactory as it frequently breaks due to its thin cantilevered construction or fails to properly hold the socket in place due to a limitation in the amount of spring force and friction that can be generated when deflected. This limitation on spring force is due to the necessity that the spring clip be made of thin material in order to wrap around the reduced thickness portion while remaining flush with the outer and inner surfaces of the drive member in the area of the reduced thickness portion. The thicker the spring is, the thinner the reduced thickness portion must be and consequently, the weaker the structure of the drive member becomes. In addition, the reduced thickness portion is complicated, relatively costly to produce, and detrimental to the structural integrity of the drive member.
A need therefore exists for an improved socket retainer which can reduce manufacturing costs and increase the amount of frictional force with which to securely hold a socket on a through-hole wrench having an inner and outer drive portion without unduly diminishing the structural integrity of the wrench.